linux-kernel - Re: [PATCH] arm64: mm: update max

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Message-ID: <61e2f232-4abe-bb10-fff5-cabe8da5a7a9@quicinc.com>
Date:   Tue, 28 Sep 2021 22:34:39 +0300
From:   Georgi Djakov <quic_c_gdjako@...cinc.com>
To:     Chris Goldsworthy <quic_cgoldswo@...cinc.com>,
        Andrew Morton <akpm@...ux-foundation.org>
CC:     David Hildenbrand <david@...hat.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        "Sudarshan Rajagopalan" <quic_sudaraja@...cinc.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
        Florian Fainelli <f.fainelli@...il.com>
Subject: Re: [PATCH] arm64: mm: update max_pfn after memory hotplug

On 9/28/2021 9:51 PM, Chris Goldsworthy wrote:
> From: Sudarshan Rajagopalan <quic_sudaraja@...cinc.com>
> 
> After new memory blocks have been hotplugged, max_pfn and max_low_pfn
> needs updating to reflect on new PFNs being hot added to system.
> Without this patch, debug-related functions that use max_pfn such as
> get_max_dump_pfn() or read_page_owner() will not work with any page in
> memory that is hot-added after boot.
> 
> Fixes: 4ab215061554 ("arm64: Add memory hotplug support")
> Signed-off-by: Sudarshan Rajagopalan <quic_sudaraja@...cinc.com>
> Signed-off-by: Chris Goldsworthy <quic_cgoldswo@...cinc.com>
> Acked-by: David Hildenbrand <david@...hat.com>

Tested-by: Georgi Djakov <quic_c_gdjako@...cinc.com>

> Cc: Florian Fainelli <f.fainelli@...il.com>
> Cc: Georgi Djakov <quic_c_gdjako@...cinc.com>
> ---
>   arch/arm64/mm/mmu.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index cfd9deb..fd85b51 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -1499,6 +1499,11 @@ int arch_add_memory(int nid, u64 start, u64 size,
>   	if (ret)
>   		__remove_pgd_mapping(swapper_pg_dir,
>   				     __phys_to_virt(start), size);
> +	else {
> +		max_pfn = PFN_UP(start + size);
> +		max_low_pfn = max_pfn;
> +	}
> +
>   	return ret;
>   }
>   
>